Subtract 30/80 from 8/42, Solve 8/42

Subtract 30/80 from 8/42

8/42 - 30/80 is -31/168.

Find the least common denominator or LCM of the two denominators:
LCM of 42 and 80 is 1680

Next, find the equivalent fraction of both fractional numbers with denominator 1680
For the 1st fraction, since 42 × 40 = 1680,
8/42 = 8 × 40/42 × 40 = 320/1680
Likewise, for the 2nd fraction, since 80 × 21 = 1680,
30/80 = 30 × 21/80 × 21 = 630/1680
Subtract the two like fractions:
320/1680 - 630/1680 = 320 - 630/1680 = -310/1680
After reducing the fraction, the answer is -31/168

MathStep (Works offline)

Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad